Comment # 52 on bug 56139 from Alexandre Demers

Also, nice to know: a suspend/resume cycle under Gnome-Shell or KDE will end up
hung. However, a suspend/resume cycle under XFCE will work correctly.

In other words, the problem seems not to be with the memory controller, but
with something that as to do with how the OpenGL/3D/else state is being
restored.